What’s in a Snaffle

By Sue Stuska Ed.D.

We recognize two main types of bits: snaffles and curbs. There are many variations on each type, and some bits combine the actions of both. We will concentrate on snaffles and curbs in this article and do more another time. Even limiting ourselves to these two categories, when we check any tack shop, catalog or online site, we find a whole array of bits—each slightly

different from the other. These are designed for different horses: some bits work differently and others fit differently. Does your horse need different action, or a different fit? The market for different bits is fueled by riders who use the slight nuances of action to find the exact key to a specific horse’s mouth. However, many other riders find one bit that works with many horses. In a lot of cases, that one bit is a snaffle.

Why a Snaffle?

Snaffles are the bit of choice for training, and, depending on the discipline, finished horses may perform in a snaffle. By the generally accepted definition, snaffles are bits that (1) allow clear direct reining and (2) work without leverage of any kind. Snaffles generally have a joint in the center of the mouthpiece, but they cannot be identified purely by the joint. Mullen mouth snaffles have no joint, while some shanked (leverage) bits have mouthpiece joints. The clarity of direct reining and the lack of leverage make snaffles ideal training bits. Direct reining means using a feel of one side of the horse’s mouth to get him to bend or turn in that direction (for example, in a one-rein stop). Green horses need assistance in learning to follow their nose. They need to learn about bend, and they need to learn to balance themselves laterally and longitudinally. Direct rein action by the right rein is a clear signal to the horse to bring his mouth/head to the right and rear. The rein moves the bit ring, which moves the right-hand part of the mouthpiece to the right and rear. The action of the rein works predominantly on the right side of the mouth. This is a very clear signal to the horse. Dr. Hilary Clayton* found that it was not possible to produce a totally independent effect on one side of the horse’s mouth with a snaffle; instead, the rein movements were transmitted through the joint to the opposite side of the bit. However, the action on the other side of the bit supports the direct rein, asking the horse to yield toward the active rein. Not coincidentally, snaffles make good bits for less experienced riders. Direct reining is generally easier for a beginning rider to understand, and snaffles are considered to be milder bits for times when the rider’s hands are not as sensitive as they should be. When both snaffle reins are used, the bit deepens the indentation in the horse’s tongue. This pressure is interpreted by the horse as a request for flexion, a slowing of forward movement, or collection of his body depending on the level of his training and the other aids in use at the time.  

Curb Leverage

Leverage involves the bit swiveling in the horse’s mouth and applying pressure down and back on the mouth and forward on the chin groove via the chin strap/chain. In a standard curb, the mouthpiece is the point of rotation, while the shanks (lengths of bit below the mouthpiece to which reins are attached) rotate backwards and the upper branches (above the level of the mouthpiece) rotate forward. If the upper branches of the bit are long enough, poll pressure and upward lip pressure are also applied as the upper branches move forward. The longer the branches or shanks, the more potential pressure. Leverage can be very useful, but it can confound the signal the horse is receiving when we use one rein—it is more challenging for the green horse to understand what we mean if a feel of the right rein no longer says “yield right” but instead says “yield right, yield from poll pressure, yield from chin pressure, and figure out what all those pressures mean on the left side of your mouth/head when felt at the same time.” Standard curbs don’t have center mouthpiece joints, and don’t tend to be flexible at the junction of bit mouthpiece and shanks. So, the whole bit tends to rotate when pressure is applied to one rein. Regardless, the bit action is more complicated and can even be confusing for the horse when the rider uses one rein to influence the direction or bend.  Even using an “opening rein” or “plow rein” (taking the rein hand way out to the side to signal a turn or bend) results in multiple different pressures on the horse’s head. Perhaps the horse is going well with gentle turns, but it becomes necessary to double him/ use a one-rein stop. The use of one rein of a curb bit is not going to give the same clear signal as a snaffle would. Therefore, (if you choose a bit), snaffles are the bit of choice for early training. The rotating action of the curb, along with the weight, balance and design of the bit (for example, a spade with its characteristic upward-projecting mouthpiece), can be used to transmit very subtle signals. They are ideal for confirming what the horse already knows, and for riding with one hand. So, curb bits are designed to be used on horses who have already attained a degree of training—including being confirmed in neck reining and the accompanying leg and weight cues. Through the centuries, horsemen have gotten horses confirmed in their work with a snaffle before changing to the curb.

Inside Views

The horse’s tongue normally lies against the hard palate. The bit indents the tongue and contacts the hard palate. The lips are also displaced by the bit passing through, and they serve to help keep the bit in position—ideally in a trusting and relaxed manner. We strive for the horse to be comfortable and trusting enough that he can hold and respond to the bit in his mouth without any tension. As we know, tension in his mouth will influence the rest of his body and result in a poorer performance than we desire. There are a number of facets of bit design and fit that influence the horse’s comfort and the bit function. We’ll discuss some of these.  

Bit Width

Bit mouthpieces are available in a variety of widths to fit different horses’ mouths. The width is measured in inches between the inner surfaces of the rings or cheek pieces. An average measurement is 5”, with ponies or large headed horses wearing smaller or larger bits, respectively. Check the fit in the horse’s mouth by straightening the joint (if there is one) and watching both corners of the mouth. The width is correct if the bit fits comfortably in the mouth without pinching the sides of the mouth (too narrow) or extending more than a quarter of an inch on either side (too wide). If you’re going bit shopping without your horse and/or are shopping online, you can measure your old bit for comparison or measure your horse’s mouth using a piece of cord stretched from one corner of the mouth to the other. Too narrow a fit pinches the cheeks against the molars. Too wide a fit will allow the joint of a jointed bit to hang too far down on the tongue, which may encourage the horse to play with the bit and possibly get his tongue over it. The story-book situation of the “bit between his teeth” is actually possible—by elevating and retracting his tongue the horse can raise the bit between his premolars (front molars). This action is easier for the horse if the bit is too wide. Extra width will also allow the bit to slide back and forth.  

Bit Height   

Bit height philosophies vary. Many horsemen hang the bit so it’s lightly in contact with the corners of the horse’s mouth. Others hang the bit lower and let the horse hold it up in the corners of his mouth. Still others look for a wrinkle or two in the corners of the lips. If you’re not with a trainer who believes otherwise, the first is a good choice. A low bit encourages the horse to mouth the bit, and if he does not choose to hold it in the corners of his lips, he may get his tongue over it. A high bit provides a degree of constant pressure, which some horsemen feel is unnecessary. Plus, some horses’ lips don’t wrinkle readily, so by the time you produce a wrinkle the bit may be unnecessarily high.

Presence, Absence and Number of Joints

The mouthpiece may be jointed or not; some mouthpieces have multiple joints. (This discussion ignores, for the moment, the connection of mouthpiece to rings, cheeks or shanks.) Joints allow the bit to bend around the tongue when the reins are used; this distributes pressure across the tongue and on the corners of the mouth. One joint in the center of the mouthpiece will cause a squeezing action on the mouth. The more joints there are (commonly two), the more the bit conforms to the shape of the tongue, and while still squeezing, the bit closes more around the mouth than it would with just one joint. Some horsemen consider this a gentler design; regardless, it is different and may or may not make any difference to your horse. The flexibility of the joints differs from one bit design to the next; the less flexible the joints, the less squeezing action will occur. An unjointed bit does not squeeze the tongue/lips but indents the tongue as a solid bar. The functional difference between jointed and unjointed snaffles is that the former allow the rider greater separate communication with one side or the other of the horse’s mouth. An unjointed curb bit may have a port (a curve in the middle) or a straight mouthpiece.  The port is designed to relieve some of the pressure on the tongue and transfer that pressure to the lips. A high port will rotate toward the roof of the mouth. Quality high-port curbs (including most spades and half-breeds) are balanced so that they align with the tongue/palate. They are designed to be used in a very subtle way by an educated rider on a highly educated horse.  

Mouthpiece Diameter

In general, a thicker mouthpiece distributes the pressure over a wider area and, therefore, is softer in its action. A thinner mouthpiece concentrates the pressure on a smaller area. However, the relative size of the horse’s oral cavity and tongue must be considered when choosing a thick mouth piece. A horse with a relatively thick tongue and/or small mouth may be uncomfortable with too much in his mouth.

Hard vs. Cushioned

Most horses go well in metal bits. However, softer rubber bits are available.  A metal mouthpiece may be wrapped with leather or latex to cushion it. Care must be taken to replace the covering before it deteriorates to the point that it might come loose.  


An infinite variety of mouthpiece textures are available. Textures vary from a milder, smooth surface to a more severe, ridged one. The mouthpiece may be angled instead of smooth and twisted lengthwise, creating spiral ridges. The bit may be wrapped with wire (without, of course, sharp ends), or the mouth piece itself may be two pieces of wire twisted together. The severity can be determined by the feel of the bit across your hand, and then by imagining the bit in the horse’s mouth. Rough textured bits are not necessarily cruel, but they are to be used by riders with educated hands.  


Relaxed and more responsive horses usually have wet, even foamy, mouths. Lubrication is likely more comfortable for the horse. While salivation is not entirely due to bit design, some bits encourage salivation. Bit variations designed to encourage a wet mouth include copper coating and rollers or keys on the mouth piece.


Well-constructed bits have smooth, even surfaces and joints. They are made of high-quality metals that last for many years. They should have a comfortable, balanced feel—both in your hand and in the horse’s mouth.


The rings to which the reins of a snaffle bit are attached come in an infinite variety of sizes and shapes. A larger bit ring is less likely to get pulled into the horse’s mouth when just one rein is used; the same with cheeks (the lower or upper and lower pieces outside the mouth that have no rein attachment). Minor variations in the shape of the rings make little difference in the action of the bit, but reflect the owner’s preference. Major variations, like cheek pieces, do affect the action of the bit. Cheek pieces touch the sides of the horse’s face and put pressure on one side of the mouth when the other rein is used. They are helpful when teaching inexperienced horses to follow their nose in a turn. The  flexibility of attachment of ring to mouthpiece is an important determinant of the amount of play in the bit. A less restricted attachment may encourage the horse to develop a wet mouth. Care must be taken with freely moving rings to ensure that the horse’s lips cannot get pinched. This is a particular problem with old bits that have worn so that the junction of joint and ring includes a gap. Rubber bit guards may be used, or the bit must be thrown away.


Bits work to communicate with horses not because they “make” the horse respond, but because the horse has learned that he can respond in a way that will result in the pressure being decreased. The rider/trainer must make the pressure-relief option available when the horse responds correctly. The more savvy the rider, the higher the level of communication attained and the lighter the horse will be to the bit. Training is the key: a horse that does not respond to a mild bit because of lack of training will not respond any better to a stronger one. If a bit ever causes pain either by design or by use, it is unlikely to elicit the desired response. The ultimate severity of any bit lies in the hands of the rider. A mild bit in abusive hands can cause torture; a strong bit in educated hands can be light and useful. The success of any bit depends on how it is used.

*Thanks to Dr. Hilary Clayton, Michigan State University, for her studies of bit fit and action. She used an X-ray machine, amplified and recorded on a video receiver/recorder, to detect what was happening inside the horse’s mouth with different bits and rein movements. Some of the insights in this article are due to her studies.

This Originally Appeared in Eclectic Horseman Issue No.25

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